Starter not turning engine over

[ignisuti]

1989 Maxum I/O with 3.0L Mercruiser engine.

Boat was running fine all weekend and then suddenly this problem occurred. I can hear the starter spin, but the it's not turning the motor.

What's the most likely cause for this?

[mcoffey]

Sounds like you need a new starter. It could be voltage drop so you should test it to be sure but in most cases if the starter spins but does not engage, the gear is stuck or the solenoid is shot. Make sure you get a Marine starter if you do replace and they are sealed units so no spark escapes and ignites those pesty fuel vapors.

[jamanati]

Here is a tip I learned from my mechanic days. Take a hammer (a real hammer, not a rubber mallet) and give the starter body (not the solenoid) a good wrap or two. If the starter starts the motor, your starter needs replacement. The hammer trick works only a couple of times as it frees up stuck bushings that are going bad.

[pascavone]

the "new" starters are $100 and the gears are plastic....... no like the old days when they rebuild them.....

Just replace the whole thing, and make sure the check the 80 amp fuse sitting on top of the hot post.

This is a $30 item that protects the whole wiring harness.

[shrew]

If it were the fuse or the solenoid, I wouldn't expect the starter to turn at all. If the boat is an 89 how old is the starter? Agreed whacking it with a hammer has worked for decades, but that is really a temporary solution. I'd think that is a sign of things to come, and it's time to rebuild or replace. For the cost of a starter, I'd just replace and be done with it.